Transgenic and genetically-engineered mutant animals provide one of the most valuable mechanisms for generating in vivo models for unraveling the molecular and genetic mechanisms of cancer and for evaluating new strategies for treatment and prevention studies. Efficient generation of transgenic animals requires great technical skill that is acquired only after extensive experience with animal husbandry and breeding, animal surgery, embryo manipulation and micromanipulation. The transgenic Animal Shared Service makes transgenic technology accessible and affordable to the members.of the University of Wisconsin Comprehensive Cancer Center. It uses the personnel, facilities and equipment of the campus-wide University of Wisconsin Biotechnology Center's Transgenic Animal Facility. Services currently provided by the Transgenic Animals Core include: Generation of transgenic mice and rats by pronuclear microinjection Cryopreservation of mouse and rat embryos Generation of knockout mice: generation of targeting vectors, generation of targeted embryonic stem (ES) cell clones, and generation of chimeric mice by injection of ES cells into host blastocyst Strain rederivations and ovarian transplants Other miscellaneous molecular biology and embryo services related to transgenic and knockout mouse production Consulting and training In addition, the staff are available for consulting at any point in the process of using the services. Considerable time is spent discussing experimental design and providing guidance on processes that they themselves are or will "be carrying out. They also train investigators in techniques such as superovulating, mating, and collecting reproductive tracts from female mice for embryo cryopreservation, isolating DMA for pronuclear micronjections, mouse handling and breeding protocols, and cutting tails and genomic DNA preparation Southern blotting to identify correctly mutated ES cells.